Usually their website will show how to connect, and say which are real. I would bet that all are real, and that whoever set it up did not want to take the time to make all the SID's the same, so they went with close variations.
But unless you know which one you are looking for, you can't tell.
For example, for Colorado Springs
- Users must have an 802.11b/g compatible wireless card installed in their computer or other device.
- Wireless network card should be set to default configuration, or DHCP-enabled.
- If your wireless card network configuration requires the name of an access point or "SSID," type "tsunami" in lower case
and they have little cards telling people how to connect